Compliant ground block and testing system having compliant ground block

ABSTRACT

A compliant ground block for a testing system for testing integrated circuit devices is disclosed. The compliant ground block includes a plurality of electrically conductive blade pairs in a side by side generally parallel relationship. Blades in the plurality of blade pairs are configured to be longitudinally slidable with respect to each other. The block also includes at least one elastomer configured to retain the plurality of blade pairs. Each blade pair of the plurality of blade pairs includes a first blade (or a first blade assembly) and a second blade. The first blade (or the first blade assembly) and the second blade are configured to generate scrubbing motions when the device under test is being pressed down on the compliant ground block or is being released from the compliant ground block.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.17/494,086 filed on Oct. 5, 2021, the entire disclosure of which ishereby incorporated by reference herein.

TECHNICAL FIELD

This disclosure relates generally to the field of testing microcircuits(e.g., chips such as semiconductor devices, integrated circuits, etc.).More specifically, the disclosure relates to compliant ground blocksthat provide electrical and/or thermal grounding to a device under test(DUT) by making contact to a load board of a testing system, and relatesto testing systems having compliant ground blocks.

BACKGROUND

The manufacturing processes for microcircuits cannot guarantee thatevery microcircuit is fully functional. Dimensions of individualmicrocircuits are microscopic and process steps very complex, so smallor subtle failures in a manufacturing process can often result indefective devices. Mounting a defective microcircuit on a circuit boardis relatively costly. Installation usually involves soldering themicrocircuit onto the circuit board. Once mounted on a circuit board,removing a microcircuit is problematic because the very act of meltingthe solder for a second time may ruin the circuit board. Thus, if themicrocircuit is defective, the circuit board itself is probably ruinedas well, meaning that the entire value added to the circuit board atthat point is lost. For all these reasons, a microcircuit is usuallytested before installation on a circuit board. Each microcircuit must betested in a way that identifies all defective devices, but yet does notimproperly identify good devices as defective. Either kind of error, iffrequent, adds substantial overall cost to the circuit boardmanufacturing process.

Microcircuit test equipment itself is quite complex. First of all, thetest equipment must make accurate and low resistance temporary andnon-destructive electrical contact with each of the closely spacedmicrocircuit contacts. Because of the small size of microcircuitcontacts and the spacing between them, even small errors in making thecontact will result in incorrect connections. A further problem inmicrocircuit test equipment arises in automated testing. Testingequipment may test one hundred devices a minute, or even more. The sheernumber of tests cause wear on the tester contacts making electricalconnections to the microcircuit terminals during testing. This weardislodges conductive debris from both the tester contacts and the deviceunder test (DUT) terminals that contaminates the testing equipment andthe DUTs themselves. The debris eventually results in poor electricalconnections during testing and false indications that the DUT isdefective. The debris adhering to the microcircuits may result in faultyassembly unless the debris is removed from the microcircuits. Removingdebris adds cost and introduces another source of defects in themicrocircuits themselves.

Other considerations exist as well. Inexpensive tester contacts thatperform well are advantageous. Minimizing the time required to replacethem is also desirable, since test equipment is expensive. If the testequipment is off line for extended periods of normal maintenance, thecost of testing an individual microcircuit increases. Test equipment incurrent use has an array of test contacts that mimic the pattern of themicrocircuit terminal array. The array of test contacts is supported ina structure that precisely maintains the alignment of the contactsrelative to each other. An alignment board or plate or template alignsthe microcircuit itself with the test contacts. The test contacts andthe alignment board are mounted on a load board having conductive padsthat make electrical connection to the test contacts. The load boardpads are connected to circuit paths that carry the signals and powerbetween the test equipment electronics and the test contacts.

One particular type of microcircuit often tested before installation hasa relatively large, centrally located ground (CG) terminal on a flat,bottom surface of the microcircuit package. The microcircuit signal andpower (S&P) terminals surround the CG terminal in a predetermined array.Microcircuit packages having this configuration of terminals may becalled CG packages. Establishing a solid ground connection to this padis critically important to get reliable test results. ICs are notentirely uniform in their production, so making reliable contact withthis ground pad is difficult.

BRIEF SUMMARY

Embodiments disclosed herein provide a solution that addresses each ofthe above-mentioned problems. Embodiments disclosed herein provide acompliant ground block that is composed of simple elements, uses anelastomeric component (e.g., made of a non-conductive material), isconfigurable to a wide-variety of shapes and sizes, can be cleaned byexisting methods without changes, is robust in a production environment,and is low-cost. In one embodiment, the compliant ground block can becomposed of a stack of blades (e.g., thin contact blades made of anelectrical and/or thermal conductive material). Each blade of the bladesis the same as each other. Each blade is inverted with respect to itsadjacent blade in a longitudinal direction of the blade or the compliantground block. Each contact blade has an elongated aperture near thecenter (e.g., below a centerline of the blade in the longitudinaldirection), with the elongated aperture axis perpendicular to the axisof compliance of the ground block. In one embodiment, the contactportion of the blade has raised teeth or protrusions that make goodcontact with the DUT and load board ground pads.

Also disclosed is a compliant ground block for a testing system fortesting integrated circuit devices. The compliant ground block includesa plurality of electrically conductive blades in a side by sidegenerally parallel relationship. The blades are configured to belongitudinally slidable with respect to each other. The block alsoincludes an elastomer configured to retain the plurality of blades. Eachblade of the plurality of blades includes a first end and a second endopposite to the first end in a longitudinal direction. The plurality ofblades is arranged so that the first end of each blade of the pluralityof blades is opposite to the first end of an adjacent blade in thelongitudinal direction, so that the first end of one blade is adjacentto the second end of the adjacent blade. The elastomer is at leasttubular (e.g., hollow or solid cylindrical) in part and non-conductive.

Also disclosed is a testing system for testing integrated circuitdevices. The testing system includes a DUT and a compliant ground block.The compliant ground block includes a plurality of blades and anelastomer configured to retain the plurality of blades. Each blade ofthe plurality of blades includes a first end and a second end oppositeto the first end in a longitudinal direction. The plurality of blades isarranged so that the first end of each blade of the plurality of bladesis opposite to the first end of an adjacent blade in the longitudinaldirection. The elastomer includes a non-conductive outer surface. Theplurality of blades includes a conductive outer surface. A size of thecompliant ground block is at least partially aligned with a ground padof the DUT.

Also disclosed is a method of assembling and positioning a compliantground block in a testing system for testing integrated circuit devices.The method includes arranging a plurality of electrically conductiveblades of the compliant ground block so that a first end of each bladeof the plurality of blades is opposite to a first end of an adjacentblade in a longitudinal direction. The first end of one blade isadjacent a second end of an adjacent blade. The second end is oppositeto the first end in the longitudinal direction. The method also includesretaining the blades with an elastomer of the compliant ground block.The blades is in a side by side generally parallel relationship. Theblades are configured to be longitudinally slidable with respect to eachother. The elastomer is at least tubular (e.g., hollow or solidcylindrical) in part and non-conductive. The method further includesinstalling the compliant ground block in a housing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

References are made to the accompanying drawings that form a part ofthis disclosure and which illustrate embodiments in which the systemsand methods described in this specification can be practiced.

FIG. 1A is a perspective view of a part of a test system for receiving aDUT for testing, according to one embodiment.

FIG. 1B is a perspective bottom view of a DUT, according to oneembodiment.

FIG. 2A is a side-view drawing of a portion of the test system forreceiving a DUT for electrical testing, according to one embodiment.

FIG. 2B is a side-view drawing of the test system of FIG. 2A, with theDUT electrically engaged, according to one embodiment.

FIG. 3 is an exploded view of building blocks of a test contactor of atest assembly for the testing of a DUT, according to one embodiment.

FIG. 4 is a perspective view of a test assembly, according to oneembodiment.

FIG. 5A is an enlarged top view of a portion of the test assembly ofFIG. 4, according to one embodiment.

FIG. 5B is an enlarged bottom view of a portion of the test assembly ofFIG. 4, according to one embodiment.

FIG. 6A is a perspective top view of a compliant ground block installedin a housing of a test contactor, according to one embodiment.

FIG. 6B is a perspective bottom view of a compliant ground blockinstalled in a housing of a test contactor, according to one embodiment.

FIG. 7A is an exploded view of a compliant ground block to be installedin a housing of a test contactor, according to one embodiment.

FIG. 7B is a perspective view of a compliant ground block, according toone embodiment.

FIG. 8A is a perspective cross-sectional view of a compliant groundblock in an uncompressed state, according to one embodiment.

FIG. 8B is an exploded cross-sectional view of a compliant ground blockin an uncompressed state, according to one embodiment.

FIG. 8C is an exploded cross-sectional view of a compliant ground blockin a compressed state, according to one embodiment.

FIG. 8D is a perspective cross-sectional view of a compliant groundblock in a compressed state, according to one embodiment.

FIG. 9A is a side view of a compliant ground block in an uncompressedstate, according to one embodiment.

FIG. 9B is a side view of a compliant ground block in a compressedstate, according to one embodiment.

FIG. 10A is a side view of a blade, according to one embodiment.

FIG. 10B is a perspective view of a blade, according to one embodiment.

FIG. 11A is a side cross-sectional view of a compliant ground block inan uncompressed state, according to one embodiment.

FIG. 11B is a side cross-sectional view of a compliant ground block in acompressed state, according to one embodiment.

FIG. 12A is a schematic view of a compliant ground block in anuncompressed state, according to one embodiment.

FIG. 12B is a schematic view of a compliant ground block in a compressedstate, according to one embodiment.

FIG. 13A is a perspective cross-sectional view of a compliant groundblock in a compressed state, according to one embodiment.

FIG. 13B is a perspective cross-sectional view of a compliant groundblock, according to one embodiment.

FIG. 14A is a perspective bottom view of a compliant ground blockinstalled in a housing of a test contactor, according to one embodiment.

FIG. 14B is a perspective cross-sectional view of a compliant groundblock installed in a housing of a test contactor, according to oneembodiment.

FIG. 14C is another perspective cross-sectional view of a compliantground block installed in a housing of a test contactor, according toone embodiment.

FIG. 14D is a perspective cross-sectional view of a compliant groundblock, according to one embodiment.

FIG. 14E is an exploded bottom view of a compliant ground block to beinstalled in a housing of a test contactor, according to one embodiment.

FIG. 14F is a side view of a blade, according to one embodiment.

FIG. 15A is a perspective bottom view of a compliant ground blockinstalled in a housing of a test contactor, according to one embodiment.

FIG. 15B is an exploded bottom view of a compliant ground block to beinstalled in a housing of a test contactor, according to one embodiment.

FIG. 15C is a side view of a blade, according to one embodiment.

FIG. 16A is a perspective view of a compliant ground block in anuncompressed state, according to one embodiment.

FIG. 16B is a perspective view of a compliant ground block in acompressed state, according to one embodiment.

FIG. 16C is a side view of a blade, according to one embodiment.

FIG. 17A is a side view of a compliant ground block in an uncompressedstate, according to one embodiment.

FIG. 17B is a side view of a compliant ground block in a compressedstate, according to one embodiment.

FIG. 18A is a perspective view of a blade, according to one embodiment.

FIG. 18B is a perspective view of a compliant ground block, according toone embodiment.

FIG. 18C is a perspective view of a blade, according to anotherembodiment.

FIG. 19A is a cross-sectional view of blades, according to oneembodiment.

FIG. 19B is a cross-sectional view of blades, according to anotherembodiment.

FIG. 19C is a cross-sectional view of blades, according to yet anotherembodiment.

FIG. 19D is a cross-sectional view of blades, according to yet anotherembodiment.

FIG. 20 is a cross-sectional view of a compliant ground block, accordingto one embodiment.

FIGS. 21A-21E are side views of a blade, according to some embodiments.

FIG. 21F is a perspective view of a blade, according to one embodiment.

FIG. 21G is a top view of a compliant ground block, according to oneembodiment.

FIG. 21H is a perspective view of a compliant ground block, according toone embodiment.

FIG. 22A is a side view of a compliant ground block, according to oneembodiment.

FIG. 22B is a perspective view of a blade pair of the compliant groundblock of FIG. 22A, according to one embodiment.

FIG. 22C is a perspective view of the compliant ground block of FIG.22A, according to one embodiment.

FIG. 22D is a cross-sectional view of the compliant ground block of FIG.22A, according to one embodiment.

FIG. 22E is an exploded view of the compliant ground block of FIG. 22Aand a housing for the compliant ground block, according to oneembodiment.

FIG. 23A is a side view of a compliant ground block, according toanother embodiment.

FIG. 23B is a perspective view of a blade pair of the compliant groundblock of FIG. 23A, according to another embodiment.

FIG. 23C is a perspective view of the compliant ground block of FIG.23A, according to another embodiment.

FIG. 23D is a cross-sectional view of the compliant ground block of FIG.23A, according to another embodiment.

FIG. 23E is an exploded view of the compliant ground block of FIG. 23Aand a housing for the compliant ground block, according to anotherembodiment.

FIG. 24A is a side view of a compliant ground block, according to yetanother embodiment.

FIG. 24B is a perspective view of a blade pair of the compliant groundblock of FIG. 24A, according to yet another embodiment.

FIG. 24C is a perspective view of the compliant ground block of FIG.24A, according to yet another embodiment.

FIG. 24D is a cross-sectional view of the compliant ground block of FIG.24A, according to yet another embodiment.

FIG. 24E is an exploded view of the compliant ground block of FIG. 24Aand a housing for the compliant ground block, according to yet anotherembodiment.

FIG. 25A is a side view of a compliant ground block, according to yetanother embodiment.

FIG. 25B is a perspective view of a blade pair of the compliant groundblock of FIG. 25A, according to yet another embodiment.

FIG. 25C is a perspective view of the compliant ground block of FIG.25A, according to yet another embodiment.

FIG. 25D is a cross-sectional view of the compliant ground block of FIG.25A, according to yet another embodiment.

FIG. 25E is an exploded view of the compliant ground block of FIG. 25Aand a housing for the compliant ground block, according to yet anotherembodiment.

FIG. 26A is a side view of a compliant ground block, according to yetanother embodiment.

FIG. 26B is a perspective view of a blade pair of the compliant groundblock of FIG. 26A, according to yet another embodiment.

FIG. 26C is a perspective view of the compliant ground block of FIG.26A, according to yet another embodiment.

FIG. 26D is a cross-sectional view of the compliant ground block of FIG.26A, according to yet another embodiment.

FIG. 26E is an exploded view of the compliant ground block of FIG. 26Aand a housing for the compliant ground block, according to yet anotherembodiment.

FIG. 27A is a side view of a compliant ground block, according to yetanother embodiment.

FIG. 27B is a perspective view of a blade pair of the compliant groundblock of FIG. 27A, according to yet another embodiment.

FIG. 27C is a perspective view of the compliant ground block of FIG.27A, according to yet another embodiment.

FIG. 27D is a cross-sectional view of the compliant ground block of FIG.27A, according to yet another embodiment.

FIG. 27E is an exploded view of the compliant ground block of FIG. 27Aand a housing for the compliant ground block, according to yet anotherembodiment.

Like reference numbers represent like parts throughout.

DETAILED DESCRIPTION

A test contactor (i.e., a part of a test assembly including alignmentplate, socket or membrane, etc.) can often provide electrical andthermal grounding to a DUT by making metal-to-metal contact to theprinted circuit board (e.g., the load board) in an oversized groundcontact area. It is very important that the force exerted by the groundcontact in no way damages the DUT integrated circuit package or cracksthe die housed within the package. A grounding system that hascompliance has advantages to a non-compliant ground block because it canaccommodate test handler, handler kit, and package tolerances. It willbe appreciated that the term “compliance” may refer to a property of amaterial of undergoing elastic deformation or change in volume whensubjected to an applied force. Compliance can be equal to the reciprocalof stiffness.

Typically, a few of the same compliant electrical contacts used for theS&P leads are used. Quite often, the limited space available in theground area limits the number of signal contacts to be placed, thusreducing the electrical and thermal effectiveness of the ground. Forexample, a limited set of contact pins can be used in the ground area.Another approach is to install a solid block of metal (e.g., a solidcopper insert) in the ground area, however that often does not workbecause of the complete or partial lack of compliance in the testsystem. In other words, the ground pad on the chip may make poor,inadequate or no contact with the ground conductor on the housing due todeviations from expected tolerances in chip package manufacture,temperature variations, misalignment by the insertion handler, etc.Another approach is to combine a metal block with compliant contactelements. This solves some of the problems in contactor groundingperformance, however it adds a tremendous amount of cost to thecontactor assembly. Another approach is to replace the metal groundblock with a Z-axis conductive elastomer. The Z-axis conductiveelastomer either has embedded wires or metallic particles suspended inthe elastomer which provides the electrical and thermal ground contacts.The drawbacks of this approach is that these type of elastomers havevery little usable compliance and easily get contaminated with debris.In some of these types of designs, a flexible metal layer may be addedto improve the life. Another approach is the incorporation of awedge-shaped metal blocks that are biased by a non-conductive elastomer.

Embodiments disclosed herein provide a compliant ground block for testcontactors and other devices that includes, for example, a stack ofplates (or blades) or other adjacent conductive elements), which in someembodiments contain an aperture that accepts an elastomer that is usedas a compliant member. The aperture, in some embodiments, in the platestack is shaped such that the compressive forces on the elastomer allowit to bulge/expand into an open cavity instead of shearing the elastomerand so that the compressive forces do not increase with deflection andmake the plates immovable.

Embodiments disclosed herein provide a solution that addresses each ofthe above-mentioned problems. Embodiments disclosed herein provide acompliant ground block that is composed of simple elements, uses anelastomeric component (e.g., made of a non-conductive material), isconfigurable to a wide-variety of shapes and sizes, can be cleaned byexisting methods without changes, is robust in a production environment,and is low-cost. In one embodiment, the compliant ground block can becomposed of a stack of blades (e.g., thin contact blades made of anelectrical and/or thermal conductive material or plating). In someembodiments, each blade of the blades is identical to lowermanufacturing costs. In other embodiments, each blade of the blades maynot be identical. Every other blade may have an inverted orientationwith respect to its adjacent blade in a height/vertical/longitudinaldirection of the blade or the compliant ground block. Each contact blademay have an elongated aperture near the center (e.g., below a centerlineof the blade in the height direction), with the elongated aperture axisperpendicular to the axis of compliance of the ground block. In oneembodiment, the contact portion of the blade may have raised teeth orprotrusions that make good contact with the DUT and load board groundpads.

FIG. 1A is a perspective view of a part of a test system 100 forreceiving a DUT 110 for testing, according to one embodiment.

The test system 100 includes a test assembly 120 for a DUT (e.g., amicrocircuit, etc.) 110. The test assembly 120 includes a load board 170that supports an alignment plate 160 having an opening or aperture 130that precisely defines the X and Y (see the coordinate indicators X andY, where the coordinate X is perpendicular to the coordinate Y, and thecoordinate Z is perpendicular to the plane of X and Y) positioning ofthe DUT 110 in test assembly 120. If the DUT 110 has orientationfeatures, it is common practice to include cooperating features inaperture 130. Load board 170 carries on its surface, connection padsconnected to a cable 180 by Signal and Power (S&P) conductors. Cable 180connects to the electronics that perform that electrical testing of theDUT 110. Cable 180 may be very short or even internal to the testassembly 120 if the test electronics are integrated with the testassembly 120, or longer if the test electronics are on a separatechassis.

A test contact array 140 having a number of individual test contactelements precisely mirrors the terminals (see 112 in FIG. 1B) carried onthe surface of the DUT 110. When the DUT 110 is inserted in the aperture130, terminals of the DUT 110 precisely align with test contact array140. The test assembly 120 is designed for compatibility with a testcontact array 140 incorporating the device. Test contact array 140 iscarried on a contact membrane or sheet or socket 150. Socket 150initially includes an insulating plastic core layer with a layer ofconductive copper on each surface of the core layer. The core layer andthe copper layers may each be on the order of 25 microns thick.Individual test contacts in array 140 are preferably formed on and insocket 150 using well-known photolithographic and laser machiningprocesses. Socket 50 has alignment features such as holes or edgepatterns located in the area between alignment plate 160 and load board170 that provide for precise alignment of socket 150 with correspondingprojecting features on alignment plate 160. All of the test contacts 140are in precise alignment with the socket 150 alignment features. In thisway, the test contacts of array 140 are placed in precise alignment withaperture 130.

FIG. 1B is a perspective bottom view of a DUT 110, according to oneembodiment. The DUT (e.g., a microcircuit, etc.) 110 includes a top mainsurface (not shown), and a bottom main surface 114 opposite to the topmain surface in the Z (see the coordinate indicators X, Y, and Z in FIG.1A) direction. In one embodiment, the DUT 110 can have flat no-leadspackages such as quad-flat no-leads (QFN) and dual-flat no-leads (DFN).Flat no-leads, also known as micro lead-frame (MLF) and SON(small-outline no leads), is a surface-mount technology, one of severalpackage technologies that connect the DUT 110 to the surfaces of e.g.,socket 150 or other printed circuit boards (PCBs) without through-holes.In one embodiment, flat no-lead can be a near chip scale plasticencapsulated package made with a planar copper lead frame substrate.Perimeter lands (e.g., terminals 112) on the package bottom provideelectrical connections to the socket 150 or the PCB. Flat no-leadpackages can include an exposed thermally conductive pad (e.g., theground pad 116 in the middle of the surface 114) to improve heattransfer out of the DUT 110 (e.g., into the PCB). The QFN package can besimilar to the quad-flat package (QFP) and a ball grid array (BGA).

FIG. 2A is a side-view drawing of a portion of the test system 100 forreceiving the DUT 110 for electrical testing, according to oneembodiment. FIG. 2B is a side-view drawing of the test system 100 ofFIG. 2A, with the DUT 110 electrically engaged, according to oneembodiment.

As shown in FIG. 2A, the DUT 110 is placed onto the test assembly 120,electrical testing is performed, and the DUT 110 is then removed fromthe test assembly 120. Any electrical connections are made by pressingcomponents into electrical contact with other components; there is nosoldering or de-soldering at any point in the testing of the DUT 110.The entire electrical test procedure may only last about a fraction of asecond, so that rapid, accurate placement of the DUT 100 becomesimportant for ensuring that the test system 100 is used efficiently. Thehigh throughput of the test assembly 120 usually requires robotichandling of the DUT 110. In most cases, an automated mechanical systemplaces the DUT 110 onto the test assembly 120 prior to testing, andremoves the DUT 110 once testing has been completed. The handling andplacement mechanism may use mechanical and optical sensors to monitorthe position of the DUT 110, and a combination of translation androtation actuators to align and place the DUT 110 on or in the testassembly 120. Alternatively, the DUT 110 may be placed by hand, orplaced by a combination of hand-fed and automated equipment.

The DUT 110 typically includes signal and power terminals 112 (see alsoterminals 112 of FIG. 1B) that connect to the socket 150 or other PCBs.The terminals may be on one side of the DUT 100, or may be on both sidesof the DUT 110. For use in the test assembly 120, all the terminals 112should be accessible from one side of the DUT 110, although it will beunderstood that there may be one or more elements on the opposite sideof the DUT 110, or that there may be other elements and/or terminals onthe opposite side that may not be tested by accessing terminals 112.Each terminal 112 is formed as a small, pad on button side of the DUT110 or possibly a lead protruding from the body of the DUT 110. Prior totesting, the pad or lead 112 is attached to an electrical lead thatconnects internally to other leads, to other electrical components,and/or to one or more chips in the DUT. The volume and size of the padsor leads may be controlled quite precisely, and there is typically notmuch difficulty caused by pad-to-pad or lead-to-lead size variations orplacement variations. During testing, the terminals 112 remain solid,and there is no melting or re-flowing of any solder.

The terminals 112 may be laid out in any suitable pattern on the surfaceof the DUT 110. In some cases, the terminals 112 may be in a generallysquare grid, which is the origin of an expression that describes the DUT110, QFN, DFN, MLF or QFP for leaded parts. There may also be deviationsaway from a rectangular grid, including irregular spacing andgeometries. It will be understood that the specific locations of theterminals may vary as needed, with corresponding locations of pads onthe load board 170 and contacts on the socket 150 or housing beingchosen to match those of the terminals 112. In general, the spacingbetween adjacent terminals 2 is in the range of 0.25 to 1.5 mm, with thespacing being commonly referred to as a “pitch”. When viewed from theside, as in FIG. 2A, the DUT 110 displays a line of terminals 112, whichmay optionally include gaps and irregular spacing. These terminals 112are made to be generally planar, or as planar as possible with typicalmanufacturing processes. In many cases, if there are chips or otherelements on the DUT 110, the protrusion of the chips is usually lessthan the protrusion of the terminals 112 away from the DUT 110.

The test assembly 120 of FIG. 2A includes a load board 170. The loadboard 170 includes a load board substrate 174 and circuitry that is usedto test electrically the DUT 110. Such circuitry may include drivingelectronics that can produce one or more AC voltages having one or moreparticular frequencies, and detection electronics that can sense theresponse of the DUT 110 to such driving voltages. The sensing mayinclude detection of a current and/or voltage at one or morefrequencies. In general, it is highly desirable that the features on theload board 170, when mounted, are aligned with corresponding features onthe DUT 110. Typically, both the DUT 110 and the load board 170 aremechanically aligned to one or more locating features on the testassembly 120. The load board 170 may include one or more mechanicallocating features, such as fiducials or precisely-located holes and/oredges, which ensure that the load board 170 may be precisely seated onthe test assembly 120. These locating features typically ensure alateral alignment (X, Y, see FIG. 1A) of the load board 170, and/or alongitudinal alignment (Z, see FIG. 1A) as well.

In general, the load board 170 may be a relatively complex and expensivecomponent. The housing/test assembly 120 performs many functionsincluding protecting the contact pads 172 of the load board 170 fromwear and damage. Such an additional element may be an interposermembrane (or socket) 150. The socket 150 also mechanically aligns withthe load board 170 with suitable locating features (not shown), andresides in the test assembly 120 above the load board 170, facing theDUT 110. The socket 150 includes a series of electrically conductivecontacts 152, which extend longitudinally outward on either side of thesocket 150. Each contact 152 may include a resilient element, such as aspring or an elastomer material, and is capable of conducting anelectrical current to/from the load board 170 from/to the DUT 110 withsufficiently low resistance or impedance. Each contact 152 may be asingle conductive unit, or may alternatively be formed as a combinationof conductive elements. In general, each contact 152 connects onecontact pad 172 on the load board 170 to one terminal 112 on the DUT110, although there may be testing schemes in which multiple contactpads 172 connect to a single terminal 112, or multiple terminals 112connect to a single contact pad 172. For simplicity, we assume in thetext and drawings that a single contact 152 connects a single pad 172 toa single terminal 112, although it will be understood that any of thetester elements disclosed herein may be used to connect multiple contactpads 172 connect to a single terminal 112, or multiple terminals 112 toa single contact pad 172.

Typically, the socket 150 electrically connects the load board pads 172and the bottom contact surface of the DUT 110. Although the socket 150may be removed and replaced relatively easily, compared with removal andreplacement of the load board 170, we consider the socket 150 to be partof the test assembly 120 for this document. During operation, the testassembly 120 includes the load board 170, the socket 150, and themechanical construction that mounts them and holds them in place (notshown). Each DUT 110 is placed against the test assembly 120, is testedelectrically, and is removed from the test assembly 120. A single socket150 may test many DUTs 110 before it wears out, and may typically lastfor several thousand tests or more before requiring replacement. Ingeneral, it is desirable that replacement of the socket 150 berelatively fast and simple, so that the test assembly 120 experiencesonly a small amount of down time for socket replacement. In some cases,the speed of replacement for the socket 150 may even be more importantthan the actual cost of each socket 150, with an increase in testerup-time resulting in a suitable cost savings during operation.

FIG. 2A shows the relationship between the test assembly 120 and theDUTs 110. When each DUT 110 is tested, it is placed into a suitablerobotic handler with sufficiently accurate placement characteristics, sothat a particular terminal 112 on the DUT 110 may be accurately andreliably placed (in X, Y and Z, see FIG. 1A) with respect tocorresponding contacts 152 on the socket 150 and corresponding contactpads 172 on the load board 170. The robotic handler (not shown) forceseach DUT 110 into contact with the test assembly 120. The magnitude ofthe force depends on the exact configuration of the test, including thenumber of terminals 112 being tested, the force to be used for eachterminal, typical manufacturing and alignment tolerances, and so forth.In general, the force is applied by the mechanical handler of the tester(not shown), acting on the DUT 110. In general, the force is generallylongitudinal, and is generally parallel to a surface normal of the loadboard 170.

FIG. 2B shows the test assembly 120 and DUT 110 in contact, withsufficient force being applied to the DUT 110 to engage the contacts 152and form an electrical connection 154 between each terminal 112 and itscorresponding contact pad 172 on the load board 170. As stated above,there may alternatively be testing schemes in which multiple terminals112 connect to a single contact pad 172, or multiple contact pads 172connect to a single terminal 112, but for simplicity in the drawings weassume that a single terminal 112 connects uniquely to a single contactpad 172.

FIG. 3 is an exploded view of the building blocks of a test contactor122 of a test assembly 120 for the testing of a DUT, according to oneembodiment. It will be appreciated that the connection assembly such asfasteners and/or parts that mount and manipulate the various buildingblocks of the testing assembly are not shown.

The test contactor 122 includes an optional stiffener 190, a socket(also known as membrane) 150, an alignment plate 160, and an optionalclamping plate 195. The stiffener 190 can provide structural support toa load board (not shown also as known as daughter board, PCB, etc., seeFIGS. 1A-2B) to minimize deflection to ensure socket 150 contacting withthe load board. The load board is used to route signals from the DUT(via the socket 150) to a tester (not shown) or vice versa. The testeris used to test the DUT (e.g., by sending commands/inputs to the DUTand/or by receiving data/outputs from the DUT). The load board ismounted to a test head in the tester. In the test assembly 120, the loadboard is disposed between the stiffener 190 and the socket 150.

The socket 150 is used to provide a pathway for inputs/outputs of theDUT to the tester (via the load board). The device alignment plate 160is to align the DUT to the socket 150. The alignment plate 160 isaligned and is attached to the stiffener 190 by e.g., fasteners that gothrough holes of the socket 150 and the load board. The alignment plate160 has a recess/opening (e.g., in the middle of the alignment plate150) with alignment features and a holder (e.g., Z direction up-stop) tohold the DUT and align the DUT to the socket 150 (so that the S&Ppins/pads/leads/balls/lines of the DUT are aligned with the S&Ppins/pads/leads/balls/lines of the socket 150).

The clamping plate 195 can be optional. The clamping plate 195 can holdthe DUT firmly against the load board (via the alignment plate 160 andthe socket 150) during testing. In one embodiment, vacuum (instead ofthe clamping plate 195) can be used as a hold down mechanism for theDUT. In another embodiment, the alignment of the DUT (by the alignmentplate 160) can be made as flush as possible, and the DUT can be held atthe corners rather than using a clamping plate.

FIG. 4 is a perspective view of a test assembly 120, according to oneembodiment. The test assembly 120 includes a socket 150 and an alignmentplate 160. The circled portion A of the test assembly 120 includes ahousing (of the test contactor).

FIG. 5A is an enlarged top view of a portion (the circled portion “A”)of the test assembly 120 of FIG. 4, according to one embodiment. FIG. 5Bis an enlarged bottom view of a portion (the circled portion “A”) of thetest assembly 120 of FIG. 4, according to one embodiment.

The test contactor includes a housing 220. A plurality of S&P terminals210 is disposed on the housing 220. The housing has an opening in e.g.,a central portion of the housing, to accommodate a block 230. In oneembodiment, the block 230 is a compliant ground block. It will beappreciated that in one embodiment, the size of the opening thataccommodating the block 230 matches the size of the ground pad 116 ofthe DUT 110 (see FIG. 1B). The S&P terminals 210 align with the S&Pterminals 112 of the DUT 110 (see FIG. 1B).

FIG. 6A is a perspective top view of a compliant ground block 230installed in a housing 220 of a test contactor, according to oneembodiment. FIG. 6B is a perspective bottom view of the compliant groundblock 230 installed in the housing 220 of the test contactor, accordingto one embodiment. It will be appreciated that the housing 220 issimplified (e.g., not showing other components of the housing as shownin FIGS. 5A and 5B).

The housing 220 includes an opening 222. As shown in FIG. 6A, on the topsurface of the housing 220, the opening 222 may include fourcircumferential curve cutouts 224 at the four corners of the opening222. The cutouts 224 can help with preventing wear and tear caused bye.g., the sharp edges of the compliant ground block 230. The compliantground block 230 includes a plurality (e.g., two, at or about 20, ormore for contact redundancy and for a big heat sink) of blades (orplates) 232 stacked together laterally in a thickness direction (e.g., Ydirection, see FIG. 1A) of the blade 232. In one embodiment, each of theblades 232 is the same as each other. A thickness of each blade is at orabout 0.050 mm. A size/area of the top surface (e.g., having arectangular or a square shape) of the compliant ground block 230 is ator about 1.1 mm². As shown in FIG. 6B, on the top surface of the housing220, the opening 222 may include two circumferential curve cutouts 226at sides of the opening opposite to each other in the thicknessdirection of the blades 232. The compliant ground block 230 includes anelastomer 234. In one embodiment, the elastomer 234 has a cylindricalshape. The elastomer 234 is wedged into the housing, thus retaining theblade stack assembly (i.e., the blades 232). In one embodiment, thediameter of the elastomer 234 is at or about 0.4 mm.

It will be appreciated that the cutouts 226 is designed to facilitatethe installation of the compliant ground block 230 from e.g., the bottomside of the housing 220. It will be appreciated that on the bottomsurface of the housing 220, the opening 222 can also include twocircumferential cutouts 226 at sides of the opening opposite to eachother in the thickness direction of the blades 232. In such embodiment,the cutouts 226 can be designed to facilitate the installation of thecompliant ground block 230 from e.g., the top side of the housing 220 aswell. In one embodiment, each blade 232 can be plated with e.g., gold,etc. In another embodiment, each blade 232 may not be plated if themetal of the blade is metallurgically suitable.

FIG. 7A is an exploded view of a compliant ground block 230 to beinstalled in a housing 220 (showing a bottom surface of the housing) ofa test contactor, according to one embodiment. FIG. 7B is a perspectiveview of a compliant ground block 230, according to one embodiment.

The blades 232 form an aperture 236 at or near the middle of the blades232, which extends in the thickness direction of the blade 232. Theelastomer 234 is inserted through the aperture 236 and is wedged intothe housing 220, thus retaining the blades 232 in the housing 220. Asshown in FIG. 7A, in one embodiment, the cutouts 224 and/or 226 mayextend from the bottom surface of the housing 220 but not reach the topsurface of the housing 220. In another embodiment, the cutouts 226 mayextend from the bottom surface of the housing 220 to the top surface ofthe housing 220.

FIG. 8A is a perspective cross-sectional view of a compliant groundblock 230 in an uncompressed state, according to one embodiment. FIG. 8Bis an exploded view of the compliant ground block 230 in theuncompressed state, according to one embodiment. FIG. 8C is an explodedview of the compliant ground block 230 in a compressed state, accordingto one embodiment. FIG. 8D is a perspective cross-sectional view of acompliant ground block 230 in the compressed state, according to oneembodiment.

FIG. 9A is a side view of a compliant ground block 230 in anuncompressed state, according to one embodiment. FIG. 9B is a side viewof a compliant ground block 230 in a compressed state, according to oneembodiment.

As shown in FIGS. 8A and 9A, the aperture 236 is elongated in awidth/transverse direction (X direction) of the blade 232 to allow forcompression of the elastomer 234. The elastomer 234 contacts the top andbottom ends of the aperture 236 in a height direction (Z direction).Cavities 238 and 240 are formed between the left and right ends of theaperture 236 in the width direction. Two blades 232 (a top 232 and abottom 232) are shown in FIGS. 9A and 9B. Each of the blades is invertedin the height direction relative to an adjacent (adjacent in thethickness direction Y) blade. For example, each blade 232 has a firstend 244 and a second end 246 opposite to the first end 244 in the heightdirection. The first end 24 of the bottom blade 232 is opposite to thefirst end 244 of the top blade 232 in the height direction. The secondend 246 of the bottom blade 232 is opposite to the second end (notshown, behind the bottom blade 232 in the thickness direction) of thetop blade 232. The aperture 236 is disposed at or near middle of thestacked blades 232. It will be appreciated that for each individualblade 232, the aperture 236 is disposed below a central line in theheight direction and is closer to the second end 246 than to the firstend 244. Each blade 232 may include a plurality of protrusions 242 atthe first end 244. In one embodiment, a distance between adjacentprotrusions 242 can be the same. In one embodiment, each blade can bemade of any conductive material such as copper, copper alloys, nickelalloys, steels, precious metals, etc. It will be appreciated thatflexibility is not a requirement with respect to the blade. Elastomercan be made of any elastic rubber-like material such as silicone, etc.In one embodiment, the elastomer may be non-conductive.

As shown in FIGS. 8D and 9B, the compliant ground block 230 is in acompressed state. The top surface of the compliant ground block 230 maycontact the ground pad 116 (see FIG. 1B) of the DUT 110. The bottomsurface of the compliant ground block 230 may contact the ground portionof the load board 170 (see FIG. 1). Forces exerted from both the groundpad 116 and the ground portion of the load board 170 can compress thecompliant ground block 230 by compressing the elastomer 234. The round(in the cross-sectional side view in FIG. 9A) elastomer may compressperpendicularly to the compression axis (in the height direction Z) andthe flow of the elastomer may move into the elongated (in the widthdirection X) open areas (cavities 238, 240) of the aperture 236. Oneadvantage of such design is that the blades 232 have some freedom togimbal over the elastomer 234 and can accommodate angular variations inthe compliant ground block 230 compression into the open areas (cavities238, 240). See e.g., FIG. 20.

FIG. 10A is a side view of a blade 232, according to one embodiment.FIG. 10B is a perspective view of a blade 232, according to oneembodiment.

As shown in FIG. 10A, a central line C1 is between the first end 244 andthe second 246, and has a same distance from the first end 244 and thesecond 246 in the height direction. A center line C2 of the aperture 236in the height direction is disposed below C1 (i.e., C2 is closer to thesecond end 246 than to the first end 244). In one embodiment, each blade232 of the stack (the compliant ground block 230) can be an identicalcomponent. In another embodiment, each blade 232 of the stack (thecompliant ground block 230) may not be identical. The first end 244 ofthe blade 232 includes a series of small protrusions (teeth) that arecontact points to the DUT pad (e.g., ground pad) or the PCB (e.g., theload board or the socket) pad (e.g., ground pad). The second end 246 ofthe blade 232 may be flat. The aperture 236 is an elongated (in thewidth direction) hole that is roughly the same diameter as the elastomer234, but has a clearance cavity (238, 240) on either side in the widthdirection. The stack (the compliant ground block 230) is assembled byalternating the teeth up and down until a predetermined number of blades232 make up the stack. The aperture 236 is centrally located laterally(in the width direction), but below center vertically (in the heightdirection)—thus resulting in the staggered up/down assembly (of thecompliant ground block 230) and allowing for the stack compression.

FIG. 11A is a side cross-sectional view of a compliant ground block 230in an uncompressed state, according to one embodiment. FIG. 11B is aside cross-sectional view of a compliant ground block 230 in acompressed state, according to one embodiment.

Compared with the uncompressed state, the first end 244 of a blade 232is closer to the second end 246 of an adjacent (adjacent in thethickness direction Y) blade 232 in the height direction Z.

FIG. 12A is a schematic view of a compliant ground block 230 in anuncompressed state, according to one embodiment. FIG. 12B is a schematicview of a compliant ground block 230 in a compressed state, according toone embodiment.

The compliant ground block 230 shows two blades (plates) 232 and theelastomer 234. The upper and lower blades slide up and down against eachother when force is applied to compress the elastomer 234. When beingcompressed, the elastomer 234 installed in the aperture 236 compressesand shears. Each blade 232 slides against the mating (adjacent) blade.Some of the elastomeric resilience is taken up by a shear-typedeformation of the elastomer 234.

FIG. 13A is a perspective cross-sectional view of a compliant groundblock 230 in a compressed state, according to one embodiment. FIG. 13Bis a perspective cross-sectional view of a compliant ground block 230,according to one embodiment.

As shown in FIG. 13A, when being compressed, the elastomer 234 alsoslightly bulges into the cavities 250 vacated by the opposing (adjacent)blade (see the bulges 248) in the height direction opposite to thedirection of the force applied. As shown in FIG. 13B, a portion “A” ofthe compressed compliant ground block 230 is enlarged. The blades 232show that the corners (see the radius 252, sized about a few microns) ofthe blades 232 in the thickness direction are not sharp. The non-sharpcorners (the radius 252) of the blades 232 can help reducing theshearing action of the blade 232 movement, and the distributed load ofthe elastomer 234 causes the elastomer 234 to squeeze into the aperturecavities (238, 240).

In a larger blade stack (e.g., the compliant ground block 230), theamount of shear can be greatly reduced because the load (e.g., the forceapplied) is distributed over the entire length of the elastomer 234.Since the edges (in the thickness direction, see also 252) of theaperture 236 also have a slight radius, thus reducing the shearingaction of the blade movement. The distributed load of the elastomer 234causes the elastomer 234 to squeeze into the aperture cavities (238,240). The sheer redundancy of the blades 232 can guarantee reliableelectrical connection of the stack. Multiple blades 232 distribute loadover elastomer 234 length, cause elastomer 234 to bulge out into openaperture cavity 250 rather than shear. Blade 232 edges (in the thicknessdirection) have small radius 252 that can minimize elastomer 234cutting.

FIG. 14A is a perspective bottom view of a compliant ground block 230 ainstalled in a housing 220 a of a test contactor, according to oneembodiment. FIG. 14B is a perspective cross-sectional view of acompliant ground block 230 a installed in a housing 220 a of a testcontactor, according to one embodiment. FIG. 14C is another perspectivecross-sectional view of a compliant ground block 230 a installed in ahousing 220 a of a test contactor, according to one embodiment. FIG. 14Dis a perspective cross-sectional view of a compliant ground block 230 a,according to one embodiment. FIG. 14E is an exploded bottom view of acompliant ground block 230 a to be installed in a housing 220 a of atest contactor, according to one embodiment. FIG. 14F is a side view ofa blade 232 a, according to one embodiment.

It will be appreciated that regarding FIG. 14A, the perspective top viewof the compliant ground block 230 a installed in the housing 220 a isthe same as FIG. 6A, where the elastomer is not visible. It will also beappreciated that unless explicitly described herein, the components,material, size, attributes, and/or properties, etc. of the compliantground block 230 a and/or the housing 220 a are the same or similar tothose of the compliant ground block 230 and/or the housing 220 describedin other embodiments.

As shown in FIGS. 14A-14C and 14E, the opening 222 a at the bottomsurface of the housing 220 a has a size that substantially matches (orfor press-fit, slightly smaller than) a size of the compliant groundblock 230 a so that the compliant ground block 230 a can be installed orinserted from the bottom of the housing 220 a. The opening 222 b at thetop surface of the housing 220 a has a size that is smaller than thesize of the compliant ground block 230 a to support/maintain/stop thecompliant ground block 230 a. The opening 222 a at the bottom surface ofthe housing 220 a extends in the height (Z) direction but does not reachthe top surface of the housing 220 a. The corners of the opening 222 aare curved to help with preventing wear and tear caused by e.g., thesharp edges of the compliant ground block 230 a.

FIG. 14B is a perspective cross-sectional view of a compliant groundblock 230 a installed in a housing 220 a, cut in the middle of thehousing 220 a along the thickness (Y) direction. FIG. 14C is aperspective cross-sectional view of the compliant ground block 230 ainstalled in the housing 220 a, cut in the middle of the housing 220 aalong the width (X) direction.

The blade 232 a has recesses (or apertures) 236 a and 236 b at sides ofthe blade 232 a in the width (X) direction. The centerline C1 of theblade is above the centerline C2 of the recesses 236 a and 236 b. Thereis no opening in the middle of the blade 232 a. Each blade 232 a isinverted with respect to its adjacent blade 232 a in the heightdirection. In one embodiment, the recesses 236 a and 236 b can have ahalf-circle shape. The elastomer 234 a can have an O-ring or other ringshape and can be stretched around blades 232 a for retention. Theelastomer 234 a can snap over the concave semicircular apertures 236 aand 236 b on both sides of the blade 232 a.

FIG. 15A is a perspective bottom view of a compliant ground block 230 binstalled in a housing 220 b of a test contactor, according to oneembodiment. FIG. 15B is an exploded bottom view of a compliant groundblock 230 b to be installed in a housing 220 b of a test contactor,according to one embodiment. FIG. 15C is a side view of a blade 232 a,according to one embodiment.

It will be appreciated that regarding FIG. 15A, the perspective top viewof the compliant ground block 230 b installed in the housing 220 b isthe same as FIG. 6A, where the elastomer is not visible. It will also beappreciated that unless explicitly described herein, the components,material, size, attributes, and/or properties, etc. of the compliantground block 230 b and/or the housing 220 b are the same or similar tothose of the compliant ground block 230 and/or the housing 220 describedin other embodiments. In one embodiment, FIG. 15C is the same as FIG.14F.

Compared with FIGS. 14A-14E, in FIGS. 15A and 15B, two individualelastomer strips 234 b are used instead of an O-ring elastomer 234 a.Each of the elastomers 234 b may have a cylindrical shape disposed oneach side of the blades 232 a in the width (X) direction. Each of theelastomers 234 b extends in the thickness (Y) direction. A length ofeach elastomer 234 b may be slightly greater than a thickness of thestacked blades 232 a. The stacked blades 232 a and each blade 232 a inin FIGS. 15A and 15B may be the same as the stacked blades 232 a andeach blade 232 a respectively in FIGS. 14A-14E.

In FIGS. 15A and 15B, the opening 222 c at the bottom surface of thehousing 220 b has an H-shape retention cut-outs, instead of the O-ringshape of 222 a. The opening 222 c has a size that substantially matches(or for press-fit, slightly smaller than) a size of the compliant groundblock 230 b so that the compliant ground block 230 b can be installed orinserted from the bottom of the housing 220 b. The opening 222 b at thetop surface of the housing 220 b has a size that is smaller than thesize of the compliant ground block 230 b to support/maintain/stop thecompliant ground block 230 b. The opening 222 b at the bottom surface ofthe housing 220 b extends in the height (Z) direction but does not reachthe top surface of the housing 220 b. The corners of the opening 222 bare curved to help with preventing wear and tear caused by e.g., thesharp edges of the compliant ground block 230 b.

FIG. 16A is a perspective view of a compliant ground block 230 c in anuncompressed state, according to one embodiment. FIG. 16B is aperspective view of the compliant ground block 230 c in a compressedstate, according to one embodiment. FIG. 16C is a side view of a blade232 b, according to one embodiment.

It will be appreciated that some DUT ground pad and/or PCB (load boardor socket) ground pad surfaces may be very delicate. The compliantground block 230 c can help to eliminate the teeth or protrusions ineach blade and can provide a gentler touch. The contact edge (e.g., thefirst end 244 a) of the blade 232 b does not include the teeth orprotrusions as in the blade 232 or 232 a. The compliant ground block 230c is designed for customer devices and/or PCB ground pads with veryfragile surfaces. It will be appreciated that the flat blade 232 b canbe combined with a tooth-blade 232 or 232 a.

As shown in FIG. 16C, the blade 232 b is the same as the blade 232 ofFIG. 10A, except that the first end 244 a of the blade 232 b is flat(without the protrusions 242). Same as the blade 232 of FIG. 10A, two orfour ends/corners of the blade 232 b are slightly trimmed to remove thesharp corners.

FIG. 17A is a side view of a compliant ground block 230 d in anuncompressed state, according to one embodiment. FIG. 17B is a side viewof the compliant ground block 230 d in a compressed state, according toone embodiment.

It will be appreciated that FIGS. 17A and 17B are the same as FIGS. 9Aand 9B, except that each blade 232 c has two or more apertures 236 c.Each aperture 236 c accommodate an elastomer 234 c. It will also beappreciated that large DUT or PCB ground pads can be accommodated by acompliant ground block 230 d that uses two or more elastomers. Suchembodiment can provide additional stability. The blade 232 c can bedivided equally in the width (X) direction based on the number of theapertures 236 c. Each aperture 236 c is centrally located laterally (inthe width direction) in each division of the blade 232 c, but belowcenter vertically (in the height direction). For example, as shown inFIGS. 17A and 17B, each blade 232 c has two apertures 236 c. The blade232 c can be divided into two parts along the width direction. Eachaperture 236 c is centrally located laterally (in the width direction)in each part of the blade 232 c, but below center vertically (in theheight direction) of that part.

FIG. 18A is a perspective view of a blade 232 d, according to oneembodiment. FIG. 18B is a perspective view of a compliant ground block230 e, according to one embodiment. FIG. 18C is a perspective view of ablade 232 e, according to another embodiment.

It will be appreciated that the blades 232 d and/or 232 e are the sameas other blades such as 232 and 232 a-232 c, except that the blades 232d and/or 232 e include bumps 260. The blade 232 d include one or morebumps 260. It will be appreciated that bump(s) may be part of the samematerial as the blade and are fabricated in the same process as theblade. The thickness of the bump(s) may be generally at or less than 10%of the thickness of the blade. As shown in FIG. 18A, the blade 232 dincludes four bumps 260 near four corners of the blade 232 d on a mainside surface of the blade. Each bump 260 has a circular or any othersuitable shape and extends (or is raised) in the thickness direction.

The blade 232 e has one or more slight flexible cantilever member 270. AU-shape opening 280 separates the cantilever member 270 from other partof the blade 232 e. The bump is disposed on or near the tip of thecantilever member 270. As shown in FIG. 18C, the blade 232 e include twoor more cantilever members 270, each cantilever member 270 is disposedbetween an end of the aperture and an edge of the blade 232 e.

The bump(s) 260 can ensure electrical reliability (e.g., electricalconnection reliability) from blade to blade, and focus the contactpoints to specific spots to guarantee reliable connection and providesome compliance in the blades stack-up.

It will be appreciated that the bumps can help to maintain goodelectrical contact among blades flat blades an slide up and down whencompressed or uncompressed, and the biasing of the blades to each otheris critical. If there are some debris between the two blades, the debriscan decrease the electrical conductivity between the two blades. Thebumps can help to improve the electrical connection between the bladeson the PCB (load board or socket) side or on the DUT side. The bumps canput high stress points through the blades. When the bumps are on the tipof the cantilever, a flexible feature can be achieved.

FIG. 19A is a cross-sectional view of blades 232 f, according to oneembodiment. FIG. 19B is a cross-sectional view of blades 232 g,according to another embodiment. FIG. 19C is a cross-sectional view ofblades 232 h, according to yet another embodiment. FIG. 19D is across-sectional view of blades 232 i, according to yet anotherembodiment.

Curved or nested blades can help to improve the electrical connectionbetween blades. The blades can be flexible members, allowing forthickness compliance. The blades can be fabricated with a curve (e.g.,in a few micron scale) in the height Z direction. When the curved bladesare stacked, higher force concentrations can improve the electricalcontact pressure and lower contact resistance. The blades (i.e., theshapes of a blade and the adjacent blade) can be nested in variousconcave and/or convex configurations, such as concave-convex nesting 232f, concave-concave nesting 232 g, and convex-convex nesting 232 h. Thecurves (convex, concave, etc.) can cause higher contact points andhigher contact pressure from blade to blade. The blades can be tilted orangled blades 232 i. Slightly angling the blades 232 i can naturallybias (e.g., creating a normal force between the blades) each bladeagainst the mating/adjacent plate over the compression cycle. The angleof the blade can vary from at or about 2 degrees to at or about 5degrees from vertical.

FIG. 20 is a cross-sectional view of a compliant ground block 230,according to one embodiment. FIG. 20 shows a DUT 110 on top of acompliant ground block 230, where the DUT 110 is not presented perfectlyflat. Such embodiment allows for a gimbaling motion—allowing for groundpads that are not flat. FIG. 20 illustrates that not only is the bladestack (i.e., the compliant ground block 230) compliant in the Zdirection, but the compliant ground block 230 allows for compliance if aDUT 110 is presented into the ground block at a slight angle, allowingfor imperfections in the part handling.

FIGS. 21A-21E are side views of a blade 232, according to someembodiments. It will be appreciated that the blade 232 of FIGS. 21A-21Ecan be the same as or similar to the blade 232 of FIGS. 10A and 10B(including the centerlines C1 and C2 as shown in FIG. 10A), except forthe differences explicitly described hereinafter.

In an embodiment, the blade 232 can include a radius 241A at one side ofthe blade 232. The blade 232 can also include a radius 241B at the otherside of the blade 232 opposite to the one side of the blade 232 in thewidth/transverse direction (X direction). The radius (241A and/or 241B)can extend from the top end 244 of the blade 232 to the bottom end 246of the blade 232. It will be appreciated that the radius (241A and/or241B) can provide improved assembly ease and allow blades 232 to tipand/or rock without catching on the housing 220.

In an embodiment, the blade 232 can include chamfer 243 at one or moreof the four corners of the blade 232. The chamfer 243 can extend fromthe side (241A or 241B) of the blade 232 to the end (244 or 246) of theblade 232. It will be appreciated that the corner chamfer(s) 243 canprovide improved assembly ease. In an embodiment, compared with theprotrusion(s) 242 of FIGS. 10A and 10B, the protrusion(s) or tip(s) 242in FIGS. 24A and 24C-24E can be larger and can provide increased lifeand better wear conditions. It will be appreciated that in an embodiment(see FIG. 21B), the blade 232 can have a flat top end 244 without anyprotrusion 242 for low inductance and/or high gain applications.

In some embodiments, compared with the aperture 236 in FIGS. 10A and10B, the apertures 236D-236F in FIGS. 21A-21E can have an increased sizeand can make room for a larger elastomer and provide more compliance. Insome embodiments, the blade 232 can have an elliptical aperture 236D, arectangular aperture 236E for increased compliance compared with theelliptical aperture, and/or an “X” shaped aperture 236F for increasedcompliance and increased contact forces compared with the ellipticalaperture.

In an embodiment, the blade 232 can include one or more relief channels245. The relief channel 245 can be disposed at a position (e.g., betweenthe protrusions 242) between the aperture (e.g., 236D-236F) and a side(241A or 241B) in the X direction. The relief channel 245 can extendfrom the top end 244 of the blade 232 to the bottom end 246 of the blade232 in the height direction (Z direction). The relief channel 245 can berecessed from the main surface of the blade 232 in the thicknessdirection (Y direction) of the blade 232. The relief channel 245 caninclude a breakoff tab 245A at an end of the relief channel 245 near thebottom end 246. Curved (e.g., in the Z direction) recesses can bedisposed at one or more of the two sides of the breakoff tab 245A in theX direction. It will be appreciated that the relief channel(s) 245 canreduce wear from the breakoff tab(s) 245A that may diminish life, andcan add clearance that prevents wear and corrosion so that the blades232 can meet the life specifications at a desired temperature.

In an embodiment, the blade 232 can include a notch (or opening) 237extending from the bottom end 246 of the blade to the aperture(236D-236F). It will be appreciated that the notch 237 can have atrapezoid shape with a base at the bottom being longer than the base atthe top of the notch 237. One or more or the bases of the notch 237 mayhave a length less than the length of the aperture (236D-236F) in the Xdirection. Notch 237 may be any discontinuity in the aperture whichallows for insertion of the elastomer. The notch or gap 237 preferablyprovides a one way opening which allows and elastomer to be receivedtherein but inhibits it removal, primarily to having a larger peripheralgap and relative to the (smaller) inner gap. This can be accomplishedwith a tapering of the gap from external to internal. The notch ispreferably in the bottom wall, but may be an intrusion in to any wall.It will also be appreciated that the notch 237 can aid in elastomerassembly in production or for field serviceability.

In some applications, surface(s) of the terminals/ground-pad of the DUTmay be plated/coated with (or may be made of) e.g., gold,nickel-palladium-gold, matte tin, or the like. In the compliant groundblock, the blade (that is configured to contact the DUT) may beplated/coated with (or may be made of) gold, palladium, or the like. Formatte tin DUT terminals/ground-pad, the debris (matte tin, generatedfrom the terminals/ground-pad) may stick onto the tips/protrusions ofthe DUT contacting blade when e.g., the DUT contacting blade is platedwith (or made of) gold, which may increase the resistance and/or reducethe performance of the compliant ground block. In an embodiment, formatte tin DUT terminals/ground-pad, the DUT contacting blade beingplated with (or made of) palladium can make the debris less sticky andcan decrease the resistance and/or increase the performance of thecompliant ground block. That is, using a palladium (plating or material)on at least the blade(s) contacting the DUT can reduce the amount ofmatte tin debris that sticks to the compliant ground block and improvethe performance of the compliant ground block. The blade(s) that isconfigured to contact the load board can be plated with (or made of)palladium as well for the same reason or with/of gold for costconsideration.

Embodiments disclosed herein can also provide scrubbing action (orscrubbing motion, scrubbing effect, scrubbing affect, or the like) sothat the DUT contacting blade(s) can slide on the surface(s) of theterminals/ground-pad of the DUT, provide self-cleaning of the debris(e.g., matte tin debris or the like), and/or knock off the debris.

FIG. 22A is a side view of a compliant ground block 301. FIG. 22B is aperspective view of a blade pair (310, 330) of the compliant groundblock 301 of FIG. 22A. FIG. 22C is a perspective view of the compliantground block 301 of FIG. 22A. FIG. 22D is a cross-sectional view of thecompliant ground block 301 of FIG. 22A. FIG. 22E is an exploded view ofthe compliant ground block 301 of FIG. 22A and a housing 401 for thecompliant ground block 301.

As shown in FIGS. 22A-22E, the compliant ground block 301 includes aplurality of electrically conductive blade pairs. The material,arrangement, and/or disposition of the blade pairs are the same as theblades or blade pairs described herein, except for the differencesexplicitly disclosed below. The plurality of blade pairs are disposed ina side by side (in Y direction or thickness direction) generallyparallel relationship. Blades in the plurality of blade pairs areconfigured to be longitudinally/vertically (Z direction, from the DUT tothe load board) slidable with respect to each other.

Each blade pair includes a first blade 310, a second blade 330, and asingle elastomer 350 configured to retain the plurality of blade pairs.The material, arrangement (including e.g., interaction with cavities 238and 240 of FIG. 9A), and/or disposition of the elastomer 350 are thesame as the elastomer(s) described herein, except for the differencesexplicitly disclosed below. The first blade 310 is configured to contactthe DUT (e.g., the ground pad/terminal), and the second blade 330 isconfigured to contact the load board (e.g., the ground pad/terminal).

The blade 310 includes a plurality of protrusions or tips 316 at an endor upper edge of the blade 310 that is configured to contact the DUT.The blade 310 may also include gaps such as flat surface(s) 318 betweenthe adjacent protrusions 316. In an embodiment, all the flat surfaces318 extend along a same line. Protrusions 316 are preferably spacedapart along at least the upper edge of the blade where it will engage aDUT contact pad.

The blade 310 further includes sides 312 and 314. In an embodiment, whenthe compliant ground block 301 is assembled and in a free state (noforce from either the DUT or from the load board is applied to thecompliant ground block 301, see FIG. 22A), the sides 312 and 314 extendin the Z direction, and the surfaces 318 extend at an angle with respectto the X direction (horizontal direction, transverse direction), so thatthe tip(s) at or towards the side 312 is disposed higher (closer to theDUT) than the tip(s) 316 at or towards the side 314. The blade 310 alsoincludes a hinge (or hinge point) 320 protruding from the side 314. Inan embodiment, the hinge 320 can be retained/fixed on the neighboringblade 330 or received within a recess in the housing so that the bladecan deflect circumferentially in response to engagement with the DUTpad. In another embodiment, or the hinge 320 can be retained/fixed within the housing 401 (e.g., into a recess of the housing) for thecompliant ground block 301.

The blade 310 may include a curved edge 322 that is configured to betangent to a portion of a periphery of the elastomer 350. The blade 310may also include a straight edge portion 324 extending and transitioningfrom an end of the curved edge 322 roughly tangent to the elastomerouter surface.

The blade 330 includes an aperture 334 for the elastomer 350 to passthrough in the Y direction. The aperture 334 is a through aperture (in Ydirection) and is contained entirely in the blade 330. The blade 330also includes sides 344 and 346, a top end 332, and radius 340 and 342at the top corners of the blade 330. In an embodiment, the end 332 ishas a flat surface extending in the X direction. At the bottom end, theblade 330 includes a plurality of protrusions or tips 336 similar totips 316. The blade 330 also includes surface(s) 338 (e.g., flatsurfaces, curved surfaces, or the like) between the adjacent protrusions336.

During operation, the DUT may come down, making contact with and/orpressing the higher tip(s) 316 at or near the side 312. The blade 310 isconfigured to swing or rotate about the hinge 320 (so that all tips 316are at a same level in the X direction) when e.g., pressed down by theDUT, causing a scrubbing action where the tips translate somewhat acrossthe face of the DUT pad. When the DUT is removed or released, theelastomer 350 can provide tension and rebound the blade 310, causing ascrubbing action. Edge 326 extends from the hinge point 320 to thecurved edge 322. It is shown here as a straight edge but may followother paths and may engage a stop (not shown) to limit downward movementof blade 310.

It will be appreciated that when the blade 310 is fully pressed by theDUT (or when the compliant ground block 301 is in the free state), theend 332 of the blade 330 is at or below the tip(s) 316 of the blade 310so that only blade 310 is contacting the DUT, and a bottom of the blade310 is at or above the tips 336 of the blade 330 so that only the blade330 is contacting the load board.

The housing 401 includes an enclosure 440, a slot 450 for the elastomer350, a slot 410 for the blade pairs (310, 330), and an opening 420 sothat the compliant ground block 301 can contact the load board when itis accommodated in the housing 401. The opening of the housing 401 (sothat the compliant ground block 301 can contact the DUT when it isaccommodated in the housing 401) is not shown.

FIGS. 23A-23E are identical to FIGS. 22A-22E, respectively, except forthe difference(s) described below between the first blade 310A of thecompliant ground block 302 in FIGS. 23A-23E and the first blade 310 inFIGS. 22A-22E. The blade 310A is identical to the blade 310, except thatthe surface/trough 319 of the blade 310A is a curved surface and thesurface/trough 318 of the blade 310 is a flat surface. In an embodiment,all the curved surfaces 319 extend along a same curved line. Thiscurvature is preferably an arc interrupted by tips/peaks 316. It will beappreciated that the curved surface(s) 319 can provide a better DUTcontact than non-curved surface(s). Trough 318 may be used to receivedebris which may fall off the DUT pad during scraping action.

FIG. 24A is a side view of a compliant ground block 501. FIG. 24B is aperspective view of a blade pair (510, 530) of the compliant groundblock 501 of FIG. 24A. FIG. 24C is a perspective view of the compliantground block 501 of FIG. 24A. FIG. 24D is a cross-sectional view of thecompliant ground block 501 of FIG. 24A. FIG. 24E is an exploded view ofthe compliant ground block 501 of FIG. 24A and a housing 601 for thecompliant ground block 501. This embodiment differs from the previousprimarily in that the hinge is another biasing elastomer.

As shown in FIGS. 24A-24E, the compliant ground block 501 includes aplurality of electrically conductive blade pairs. The material,arrangement, and/or disposition of the blade pairs are the same as theblades or blade pairs described herein, except for the differencesexplicitly disclosed below. The plurality of blade pairs are disposed ina side by side (in Y direction or thickness direction) generallyparallel relationship. Blades in the plurality of blade pairs areconfigured to be longitudinally/vertically (Z direction, from the DUT tothe load board) slidable with respect to each other.

Each blade pair includes a first blade 510, a second blade 530, and twoelastomers (550A, 550B) configured to retain the plurality of bladepairs. The material, arrangement, and/or disposition of the elastomers550A, 550B are the same as the elastomer(s) described herein, except forthe differences explicitly disclosed below. The first blade 510 isconfigured to contact the DUT (e.g., the ground pad/terminal), and thesecond blade 530 is configured to contact the load board (e.g., theground pad/terminal).

The blade 310 includes a plurality of protrusions or tips 516 at an endof the blade 510 that is configured to contact the DUT. The blade 510also includes flat surface(s) 518 between the adjacent protrusions 516.In an embodiment, all the flat surfaces 518 extend along a same line. Inthe alternative, the blat surfaces 518 may be arcuate in the same way asthey are in FIG. 23B.

The blade 510 further includes sides 512 and 514. In an embodiment, whenthe compliant ground block 501 is assembled and in a free state (noforce from either the DUT or from the load board is applied to thecompliant ground block 501, see FIG. 24A), the sides 512 and 514 extendin the Z direction, and the surfaces 518 extend at an angle with respectto the X direction (horizontal direction, transverse direction), so thatthe tip(s) at or towards the side 512 is disposed higher (closer to theDUT) than the tip(s) 516 at or towards the side 514.

The blade 510 includes a curved edge or recess 524 on side 514 that isconfigured to be tangent to a portion of a periphery of the elastomer550A, and a curved edge or recess 522 on side 512 that is configured tobe tangent to a portion of a periphery of the elastomer 550B. In a freestate or being pressed by the DUT, the recess 522 is disposed below therecess 524 in the X direction.

The blade 530 includes sides 543 and 545, a top end 532, and radius 540and 542 at the top corners of the blade 530. In an embodiment, the end532 is has a flat surface extending in the X direction. At the bottomend, the blade 530 includes a plurality of protrusions or tips 536. Theblade 530 also includes surface(s) 538 (e.g., flat surfaces, curvedsurfaces, or the like) between the adjacent protrusions 536.

The blade 530 also includes an elongated recess with a curved edge orrecess 544 on side 545 that is configured to be tangent to a portion ofa periphery of the elastomer 550B, and a curved edge or recess 546 onside 543 that is configured to be tangent to a portion of a periphery ofthe elastomer 550A. In a free state or being pressed by the DUT, therecess 544 is disposed below the recess 546 in the X direction. Theelastomer 550A is configured to be biased into the recesses 524 and 546,and the elastomer 550B is configured to be biased into the recesses 522and 544.

It will be appreciated that in blade 530, if the side 545 extends in itsoriginal direction, the elastomer 550B may be entirely enclosed by theside 545 and the recess 544. For recesses 522, 524, and 546, if thecorresponding side extends in its original direction, the correspondingelastomer is partially (not entirely) enclosed by the corresponding sideand the corresponding recess.

In an embodiment, the elastomers (550A, 550B) can have the samedurometers. In another embodiment, the elastomers (550A, 550B) can havedifferent durometers to make the blade 510 swing/rotate more (e.g., 550Ahas a softer durometer than 550B). It will be appreciated that having anelastomer on the short or hinging side 514 of the blade 510 can providethe blade 510 more freedom to move. If the elastomer at the reboundingside 512 has a softer durometer, the blade can move further. In fact,the durometers of all elastomers can vary stepwise or segment-wise alongits longitudinal extent, or continuously varied, according to userneeds.

During operation, the DUT may come down, making contact with and/orpressing the higher tip(s) 516 at or near the side 512, and the wholeblade 510 may come down as a result from the top side first, creating ascrubbing action as the tip(s) 516 slides along and the lower tip(s) 516makes contact with the DUT one after the other. As the blade 510rotates, the tips 516 may scrub along the ground pad of the DUT causingthe scrubbing effect (for both rotation and lateral movement). That is,the blade 510 is configured to swing or rotate (e.g., due to its shape)about an axis (not shown) (so that all tips 516 are at a same level inthe X direction) when e.g., pressed down by the DUT, causing a scrubbingaction. When the DUT is removed or released, the elastomers 550A and550B can provide tension and rebound the blade 510, causing a scrubbingaction.

It will be appreciated that when the blade 510 is fully pressed by theDUT (or when the compliant ground block 501 is in the free state), theend 532 of the blade 530 is at or below the tip(s) 516 of the blade 510so that only blade 510 is contacting the DUT, and a bottom 526 of theblade 510 is at or above the tips 536 of the blade 530 so that only theblade 530 is contacting the load board. Blade 510 also differs fromblade 310A in there is an accurate extension that partially surroundselastomer 550B. Elastomer 550B is surrounded roughly halfway around bythis extension.

The housing 601 includes an enclosure 640, a slot 650A for the elastomer550A, a slot 650B for the elastomer 550B, a slot 610 for the blade pairs(610, 630), and an opening 620 so that the compliant ground block 501can contact the load board when it is accommodated in the housing 601.The opening of the housing 601 (so that the compliant ground block 501can contact the DUT when it is accommodated in the housing 601) is notshown.

FIGS. 25A-25E are identical to FIGS. 24A-24E, respectively, except forthe difference(s) described below between the first blade 510A of thecompliant ground block 502 in FIGS. 25A-25E and the first blade 510 inFIGS. 24A-24E. The blade 510A is identical to the blade 510, except thatthe surface 519 of the blade 510A is a curved surface and the surface518 of the blade 510 is a flat surface. In an embodiment, all the curvedsurfaces 519 extend along a same curved line. It will be appreciatedthat the curved surface(s) 519 can provide a better DUT contact thannon-curved surface(s).

FIG. 26A is a side view of a compliant ground block 700. FIG. 26B is aperspective view of a blade pair (710, 730) of the compliant groundblock 700 of FIG. 26A. FIG. 26C is a perspective view of the compliantground block 700 of FIG. 26A. FIG. 26D is a cross-sectional view of thecompliant ground block 700 of FIG. 26A. FIG. 26E is an exploded view ofthe compliant ground block 700 of FIG. 26A and a housing 701 for thecompliant ground block 700.

As shown in FIGS. 26A-26E, the compliant ground block 700 includes aplurality of electrically conductive blade pairs. The material,arrangement, and/or disposition of the blade pairs are the same as theblades or blade pairs described herein, except for the differencesexplicitly disclosed below. The plurality of blade pairs are disposed ina side by side (in Y direction or thickness direction) generallyparallel relationship. Blades in the plurality of blade pairs areconfigured to be longitudinally/vertically (Z direction, from the DUT tothe load board) slidable with respect to each other.

Each blade pair includes a first blade 710, a second blade 730, and asingle elastomer 750 configured to retain the plurality of blade pairs.The material, arrangement, and/or disposition of the elastomer 750 arethe same as the elastomer(s) described herein, except for thedifferences explicitly disclosed below. The first blade 710 isconfigured to contact the DUT (e.g., the ground pad/terminal), and thesecond blade 730 is configured to contact the load board (e.g., theground pad/terminal).

The blade 710 includes a plurality of protrusions or tips 716 at an endof the blade 710 that is configured to contact the DUT. The blade 710also includes flat surface(s) 718 between the adjacent protrusions 716.In an embodiment, all the flat surfaces 718 extend along a same line. Inanother embodiment, instead of flat surface(s) 718, there can be curvedsurface(s) between the adjacent protrusions 716. All the curved surfacescan extend along a same curved line. It will be appreciated that thecurved surface(s) can provide a better DUT contact than non-curvedsurface(s).

The blade 710 further includes sides 712 and 714. In an embodiment, whenthe compliant ground block 700 is assembled and in a free state (noforce from either the DUT or from the load board is applied to thecompliant ground block 700, see FIG. 26A), the sides 712 and 714 extendin the Z direction, the surfaces 718 extend in the X direction(horizontal direction, transverse direction), and all tips 716 are at asame level in the X direction.

The blade 710 includes a curved edge 724 that is configured to betangent to a portion of a periphery of the elastomer 750. The blade 710also includes a straight edge 725 extending from an end of the curvededge 724. The blade 710 further includes a sliding edge 722 extendingfrom the side 712 to the bottom end 726 of the blade 710.

The blade 730 includes a recess 748 (on side 746) that is configured tobe tangent to a portion of a periphery of the elastomer 750. Theelastomer 750 is configured to be biased into the recess 748 and thecurved edge 724. The blade 730 also includes sides 744 and 746, a topend 732, and radius 740 and 742 at the top corners of the blade 730. Inan embodiment, the end 732 is has a flat surface extending in the Xdirection. At the bottom end, the blade 730 includes a plurality ofprotrusions or tips 736. The blade 730 also includes surface(s) 738(e.g., flat surfaces, curved surfaces, or the like) between the adjacentprotrusions 736.

In an embodiment, the blade 730 includes a ramp preferably having anoutwardly protruding ledge 734 partitioning the second blade into afirst portion 733 and a second portion 735 along the ramp 734. Athickness of the first portion 733 is greater than a thickness of thesecond portion 735 extends from a point at or near the radius 740 to apoint at or near a middle of the bottom end of blade 730. The ramp 734is configured to support the sliding edge 722. A thickness of the firstportion 733 is greater than a thickness of the second portion 735 sothat the sliding edge 722 can slide along the ramp 734 when the blade710 is pressed by the DUT. In an embodiment, the thickness of the firstportion 733 is the thickness of the second portion 735 plus a thicknessof the blade 710.

In another embodiment, the housing 701 includes a support structure (notshown) to support the sliding edge 722 so that the sliding edge 722 canslide along the support structure.

During operation, the DUT may come down, making contact with and/orpressing and/or pushing down on the tip(s) 716 of blade 710. The blade710 is configured to slide along/down the ramp 734 (or along/down thesupport structure of the housing 701) and push against the elastomer 750(one side of the elastomer 750 holding in the housing 701 and anotherside holding in the neighboring blade 730) to retain tension when e.g.,pressed down by the DUT, causing a scrubbing action. When the DUT isremoved or released, the elastomer 750 can provide tension and reboundthe blade 710 so that the blade 710 slides/returns back/up to itsoriginal position in a free state, causing a scrubbing action.

It will be appreciated that when the blade 710 is fully pressed by theDUT (or when the compliant ground block 700 is in the free state), theend 732 of the blade 730 is at or below the tip(s) 716 of the blade 710so that only blade 710 is contacting the DUT, and a bottom 726 of theblade 710 is at or above the tips 736 of the blade 730 so that only theblade 730 is contacting the load board.

The housing 701 includes an enclosure 704, a slot 705 for the elastomer750, a slot 703 for the blade pairs (710, 730), and an opening 702 sothat the compliant ground block 700 can contact the load board when itis accommodated in the housing 701. The opening of the housing 701 (sothat the compliant ground block 700 can contact the DUT when it isaccommodated in the housing 701) is not shown.

FIG. 27A is a side view of a compliant ground block 800. FIG. 27B is aperspective view of a blade pair (810A and 810B, 830) of the compliantground block 800 of FIG. 27A. FIG. 27C is a perspective view of thecompliant ground block 800 of FIG. 27A. FIG. 27D is a cross-sectionalview of the compliant ground block 800 of FIG. 27A. FIG. 27E is anexploded view of the compliant ground block 800 of FIG. 27A and ahousing 801 for the compliant ground block 800.

As shown in FIGS. 27A-27E, the compliant ground block 800 includes aplurality of electrically conductive blade pairs. The material,arrangement, and/or disposition of the blade pairs are the same as theblades or blade pairs described herein, except for the differencesexplicitly disclosed below. The plurality of blade pairs are disposed ina side by side (in Y direction or thickness direction) generallyparallel relationship. Blades in the plurality of blade pairs areconfigured to be longitudinally/vertically (Z direction, from the DUT tothe load board) slidable with respect to each other.

Each blade pair includes a first blade assembly (810A, 810B), a secondblade 830, and two elastomers (850A, 850B) and an optional elastomer850C configured to retain the plurality of blade pairs. The material,arrangement (including e.g., interaction with cavities 238 and 240 ofFIG. 9A), and/or disposition of the elastomers (850A, 850B, 850C) arethe same as the elastomer(s) described herein, except for thedifferences explicitly disclosed below. The blade assembly (810A, 810B)is configured to contact the DUT (e.g., the ground pad/terminal), andthe second blade 830 is configured to contact the load board (e.g., theground pad/terminal).

In an embodiment, the blade assembly includes a first portion 810A and asecond portion 810B that mirror each other in the Z direction.

The portion 810A includes two or more protrusions or tips 816 at an endof the portion 810A that is configured to contact the DUT. The portion810A also includes flat surface(s) 818 between the adjacent protrusions816. In an embodiment, all the flat surfaces 818 extend along a sameline. In another embodiment, instead of flat surface(s) 818, there canbe curved surface(s) between the adjacent protrusions 816. All thecurved surfaces can extend along a same curved line. It will beappreciated that the curved surface(s) can provide a better DUT contactthan non-curved surface(s).

The portion 810A further includes sides 812 and 814. In an embodiment,when the compliant ground block 800 is assembled and in a free state (noforce from either the DUT or from the load board is applied to thecompliant ground block 800, see FIG. 27A), the side 814 extends in the Zdirection, and the surface(s) 818 extends at an angle with respect tothe X direction (horizontal direction, transverse direction), so thatthe tip(s) 816 at or towards the side 814 is disposed higher (closer tothe DUT) than the tip(s) 816 at or towards the side 812.

The portion 810A includes an edge 820 extending from an end of side 814toward a bottom 822 of the portion 810A. The edge 820 and the side 812intersect at or around the bottom 822.

The portion 810B includes two or more protrusions or tips 816 at an endof the portion 810B that is configured to contact the DUT. The portion810B also includes flat surface(s) 818 between the adjacent protrusions816. In an embodiment, all the flat surfaces 818 extend along a sameline. In another embodiment, instead of flat surface(s) 818, there canbe curved surface(s) between the adjacent protrusions 816. All thecurved surfaces can extend along a same curved line. It will beappreciated that the curved surface(s) can provide a better DUT contactthan non-curved surface(s).

The portion 810B further includes sides 812 and 814. In an embodiment,when the compliant ground block 800 is assembled and in a free state (noforce from either the DUT or from the load board is applied to thecompliant ground block 800, see FIG. 27A), the side 814 extends in the Zdirection, and the surface(s) 818 extends at an angle with respect tothe X direction (horizontal direction, transverse direction), so thatthe tip(s) 816 at or towards the side 814 is disposed higher (closer tothe DUT) than the tip(s) 816 at or towards the side 812.

The portion 810B includes an edge 820 extending from an end of side 814toward a bottom 822 of the portion 810A. The edge 820 and the side 812intersect at or around the bottom 822.

The portion 810A mirrors the portion 810B in the Z direction. Theportion 810A and the portion 810B define or form a “V” shape recess.Hinge or pivot points (not show) is at or around the bottom(s) 822 sothat the portion 810A and the portion 810B can rotate about the hinges.

The blade 830 includes sides 844 and 846, a top end 832, and radius 840and 842 at the top corners of the blade 830. In an embodiment, the end832 is has a flat surface extending in the X direction. At the bottomend, the blade 830 includes a plurality of protrusions or tips 836. Theblade 830 also includes surface(s) 838 (e.g., flat surfaces, curvedsurfaces, or the like) between the adjacent protrusions 836.

The blade 830 includes a recess 845 (on side 844) that is configured tobe tangent to a portion of a periphery of the elastomer 850A. Theelastomer 850A is configured to be biased into the recess 845 and theedge 820 of the portion 810A. The blade 830 also includes a recess 847(on side 846) that is configured to be tangent to a portion of aperiphery of the elastomer 850B. The recess 845 is disposed at a samelevel as the recess 847 in a horizontal direction. The elastomer 850B isconfigured to be biased into the recess 847 and the edge 820 of theportion 810B.

The blade 830 can include an optional aperture 834 for the optionalelastomer 850C to pass through in the Y direction. The aperture 834 is athrough aperture (in Y direction) and is contained entirely in the blade830. The elastomer 850C is disposed in the V-shape recess formed by side812. In an embodiment, the elastomer 850C is smaller (e.g., has asmaller diameter) than the elastomers 850A and 850B. It will beappreciated that a small elastomer in the middle (of the blade 830 or ofthe blade assembly 810A and 810B) (for retention features) can keeptension and keep the parts in place.

During operation, the DUT may come down, making contact with and/orpressing the higher tip(s) 316 at or near the side 814 (of the portion810A and the portion 810B). The blade assembly (810A, 810B) isconfigured to rotate about the hinge (so that all tips 816 are at a samelevel in the X direction) when e.g., pressed down by the DUT, causing ascrubbing action. When the DUT is removed or released, the elastomers(850A, 850B) can provide tension and rebound the blade assembly (810A,810B), causing a scrubbing action.

That is, when the DUT presses down, forcing the two portions (810A,810B) to further open and create a scrubbing effect on the DUT. The twoportions (810A, 810B) may press against the elastomers (850A, 850B) andcreate tension. When the DUT is removed or released, the elastomers(850A, 850B) may return the two portions (810A, 810B) back to theirposition in a free state. The elastomers (850A, 850B) are disposed at oron the sides (844, 846), the blade 830 is facing down, and the twoportions (810A, 810B) (e.g., two smaller triangular blades) are sittingin between the elastomers (850A, 850B). When the DUT presses down, itmay force the two portions (810A, 810B) to rock/rotate around/againstthe hinge (i.e., the pivot point) and create scrubbing motion.

It will be appreciated that when the two portions (810A, 810B) are fullypressed by the DUT (or when the compliant ground block 800 is in thefree state), the end 832 of the blade 830 is at or below the tip(s) 816of the blade assembly (810A, 810B) so that only the blade assembly(810A, 810B) is contacting the DUT, and a bottom 822 of the bladeassembly (810A, 810B) is at or above the tips 836 of the blade 830 sothat only the blade 830 is contacting the load board.

The housing 801 includes an enclosure 804, a slot 805A for the elastomer850A, a slot 805B for the elastomer 850B, an optional slot 805C for theoptional elastomer 850C, a slot 803 for the blade pairs (810A and 810B,830), and an opening 802 so that the compliant ground block 800 cancontact the load board when it is accommodated in the housing 801. Theopening of the housing 801 (so that the compliant ground block 800 cancontact the DUT when it is accommodated in the housing 801) is notshown.

The description of the invention and its applications as set forthherein is illustrative and is not intended to limit the scope of theinvention. Variations and modifications of the embodiments disclosedherein are possible and practical alternatives to and equivalents of thevarious elements of the embodiments would be understood to those ofordinary skill in the art upon study of this patent document. These andother variations and modifications of the embodiments disclosed hereinmay be made without departing from the scope and spirit of theinvention.

Aspects

It is noted that any one of aspects below can be combined with eachother.

Aspect 1. A compliant ground block for a testing system for testingintegrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by sidegenerally parallel relationship, blades in the plurality of blade pairsconfigured to be longitudinally slidable with respect to each other; and

an elastomer configured to retain the plurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a firstblade and a second blade,

the first blade includes a hinge and a curved edge tangent to a portionof a periphery of the elastomer, the first blade is configured to rotateabout the hinge when pressed,

the second blade includes an aperture for the elastomer to pass through.

Aspect 2. The compliant ground block according to aspect 1, wherein thefirst blade includes a plurality of protrusions at an end of the firstblade.

Aspect 3. The compliant ground block according to aspect 2, wherein thefirst blade includes curved surfaces between adjacent protrusions of theplurality of protrusions.

Aspect 4. The compliant ground block according to aspect 2, wherein thefirst blade includes flat surfaces between adjacent protrusions of theplurality of protrusions.

Aspect 5. The compliant ground block according to any one of aspects1-4, wherein the aperture is a through aperture and is containedentirely in the second blade.

Aspect 6. A compliant ground block for a testing system for testingintegrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by sidegenerally parallel relationship, blades in the plurality of blade pairsconfigured to be longitudinally slidable with respect to each other; and

a first elastomer and a second elastomer configured to retain theplurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a firstblade and a second blade,

the first blade includes a first recess on a first side of the firstblade and a second recess on a second side of the first blade, thesecond recess of the first blade is disposed below the first recess ofthe first blade in a horizontal direction,

the second blade includes a first recess on a first side of the secondblade and a second recess on a second side of the second blade, thesecond recess of the second blade is disposed below the first recess ofthe second blade in a horizontal direction.

Aspect 7. The compliant ground block according to aspect 6, wherein thefirst blade includes a plurality of protrusions at an end of the firstblade.

Aspect 8. The compliant ground block according to aspect 7, wherein thefirst blade includes curved surfaces between adjacent protrusions of theplurality of protrusions.

Aspect 9. The compliant ground block according to aspect 7, wherein thefirst blade includes flat surfaces between adjacent protrusions of theplurality of protrusions.

Aspect 10. The compliant ground block according to any one of aspects6-9, wherein the first elastomer is configured to be biased into thefirst recess of the first blade and the first recess of the secondblade, and the second elastomer is configured to be biased into thesecond recess of the first blade and the second recess of the secondblade.

Aspect 11. A compliant ground block for a testing system for testingintegrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by sidegenerally parallel relationship, blades in the plurality of blade pairsconfigured to be longitudinally slidable with respect to each other; and

an elastomer configured to retain the plurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a firstblade and a second blade,

the first blade includes a recess on a first side of the first blade anda sliding edge extending from a second side of the first blade to abottom end of the first blade,

the second blade includes a recess at a first side of the second blade,

the elastomer is configured to be biased into the recess of the firstblade and the recess of the second blade.

Aspect 12. The compliant ground block according to aspect 11, whereinthe first blade includes a plurality of protrusions at an end of thefirst blade.

Aspect 13. The compliant ground block according to aspect 12, whereinthe first blade includes curved surfaces between adjacent protrusions ofthe plurality of protrusions.

Aspect 14. The compliant ground block according to aspect 12, whereinthe first blade includes flat surfaces between adjacent protrusions ofthe plurality of protrusions.

Aspect 15. The compliant ground block according to any one of aspects11-14, wherein the second blade includes a ramp partitioning the secondblade into a first portion and a second portion along the ramp, the rampis configured to support the sliding contact, a thickness of the firstportion is greater than a thickness of the second portion.

Aspect 16. A compliant ground block for a testing system for testingintegrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by sidegenerally parallel relationship, blades in the plurality of blade pairsconfigured to be longitudinally slidable with respect to each other; and

a first elastomer and a second elastomer configured to retain theplurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a firstblade assembly and a second blade,

the first blade assembly includes a first portion and a second portion,the first portion of the first blade assembly and the second portion ofthe first blade assembly define a “V” shape recess,

the second blade includes a first recess on a first side of the secondblade and a second recess on a second side of the second blade, thefirst recess of the second blade is disposed at a same level as thesecond recess of the second blade in a horizontal direction.

Aspect 17. The compliant ground block according to aspect 16, whereinthe first blade assembly includes a plurality of protrusions at an endof the first blade assembly.

Aspect 18. The compliant ground block according to aspect 17, whereinthe first blade assembly includes curved surfaces between adjacentprotrusions of the plurality of protrusions.

Aspect 19. The compliant ground block according to aspect 17, whereinthe first blade assembly includes flat surfaces between adjacentprotrusions of the plurality of protrusions.

Aspect 20. The compliant ground block according to any one of aspects16-19, wherein the first elastomer is configured to be biased into thefirst recess of the second blade, and the second elastomer is configuredto be biased into the second recess of the second blade.

Aspect 21. The compliant ground block according to any one of aspects16-20, further comprising a third elastomer,

the second blade includes an aperture for the third elastomer to passthrough, the aperture is a through aperture and is contained entirely inthe second blade.

The terminology used in this specification is intended to describeparticular embodiments and is not intended to be limiting. The terms“a,” “an,” and “the” include the plural forms as well, unless clearlyindicated otherwise. The terms “comprises” and/or “comprising,” whenused in this specification, specify the presence of the stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, and/or components.

With regard to the preceding description, it is to be understood thatchanges may be made in detail, especially in matters of the constructionmaterials employed and the shape, size, and arrangement of parts withoutdeparting from the scope of the present disclosure. This specificationand the embodiments described are exemplary only, with the true scopeand spirit of the disclosure being indicated by the claims that follow.

What is claimed is:
 1. A compliant ground block for a testing system fortesting integrated circuit devices, comprising: a plurality ofelectrically conductive blade pairs in a side by side generally parallelrelationship, blades in the plurality of blade pairs configured to belongitudinally slidable with respect to each other; and an elastomerconfigured to retain the plurality of blade pairs, wherein each bladepair of the plurality of blade pairs includes a first blade and a secondblade, the first blade includes a hinge and a curved edge tangent to aportion of a periphery of the elastomer, the first blade is configuredto rotate about the hinge when pressed, the second blade includes anaperture for the elastomer to pass through.
 2. The compliant groundblock according to claim 1, wherein the first blade includes a pluralityof protrusions at an end of the first blade.
 3. The compliant groundblock according to claim 2, wherein the first blade includes curvedsurfaces between adjacent protrusions of the plurality of protrusions.4. The compliant ground block according to claim 2, wherein the firstblade includes flat surfaces between adjacent protrusions of theplurality of protrusions.
 5. The compliant ground block according toclaim 1, wherein the aperture is a through aperture and is containedentirely in the second blade.
 6. A compliant ground block for a testingsystem for testing integrated circuit devices, comprising: a pluralityof electrically conductive blade pairs in a side by side generallyparallel relationship, blades in the plurality of blade pairs configuredto be longitudinally slidable with respect to each other; and a firstelastomer and a second elastomer configured to retain the plurality ofblade pairs, wherein each blade pair of the plurality of blade pairsincludes a first blade and a second blade, the first blade includes afirst recess on a first side of the first blade and a second recess on asecond side of the first blade, the second recess of the first blade isdisposed below the first recess of the first blade in a horizontaldirection, the second blade includes a first recess on a first side ofthe second blade and a second recess on a second side of the secondblade, the second recess of the second blade is disposed below the firstrecess of the second blade in a horizontal direction.
 7. The compliantground block according to claim 6, wherein the first blade includes aplurality of protrusions at an end of the first blade.
 8. The compliantground block according to claim 7, wherein the first blade includescurved surfaces between adjacent protrusions of the plurality ofprotrusions.
 9. The compliant ground block according to claim 7, whereinthe first blade includes flat surfaces between adjacent protrusions ofthe plurality of protrusions.
 10. The compliant ground block accordingto claim 6, wherein the first elastomer is configured to be biased intothe first recess of the first blade and the first recess of the secondblade, and the second elastomer is configured to be biased into thesecond recess of the first blade and the second recess of the secondblade.
 11. A compliant ground block for a testing system for testingintegrated circuit devices, comprising: a plurality of electricallyconductive blade pairs in a side by side generally parallelrelationship, blades in the plurality of blade pairs configured to belongitudinally slidable with respect to each other; and an elastomerconfigured to retain the plurality of blade pairs, wherein each bladepair of the plurality of blade pairs includes a first blade and a secondblade, the first blade includes a recess on a first side of the firstblade and a sliding edge extending from a second side of the first bladeto a bottom end of the first blade, the second blade includes a recessat a first side of the second blade, the elastomer is configured to bebiased into the recess of the first blade and the recess of the secondblade.
 12. The compliant ground block according to claim 11, wherein thefirst blade includes a plurality of protrusions at an end of the firstblade.
 13. The compliant ground block according to claim 12, wherein thefirst blade includes curved surfaces between adjacent protrusions of theplurality of protrusions.
 14. The compliant ground block according toclaim 12, wherein the first blade includes flat surfaces betweenadjacent protrusions of the plurality of protrusions.
 15. The compliantground block according to claim 11, wherein the second blade includes aramp partitioning the second blade into a first portion and a secondportion along the ramp, the ramp is configured to support the slidingcontact, a thickness of the first portion is greater than a thickness ofthe second portion.
 16. A compliant ground block for a testing systemfor testing integrated circuit devices, comprising: a plurality ofelectrically conductive blade pairs in a side by side generally parallelrelationship, blades in the plurality of blade pairs configured to belongitudinally slidable with respect to each other; and a firstelastomer and a second elastomer configured to retain the plurality ofblade pairs, wherein each blade pair of the plurality of blade pairsincludes a first blade assembly and a second blade, the first bladeassembly includes a first portion and a second portion, the firstportion of the first blade assembly and the second portion of the firstblade assembly define a “V” shape recess, the second blade includes afirst recess on a first side of the second blade and a second recess ona second side of the second blade, the first recess of the second bladeis disposed at a same level as the second recess of the second blade ina horizontal direction.
 17. The compliant ground block according toclaim 16, wherein the first blade assembly includes a plurality ofprotrusions at an end of the first blade assembly.
 18. The compliantground block according to claim 17, wherein the first blade assemblyincludes curved surfaces between adjacent protrusions of the pluralityof protrusions.
 19. The compliant ground block according to claim 17,wherein the first blade assembly includes flat surfaces between adjacentprotrusions of the plurality of protrusions.
 20. The compliant groundblock according to claim 16, wherein the first elastomer is configuredto be biased into the first recess of the second blade, and the secondelastomer is configured to be biased into the second recess of thesecond blade.